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Difference between revisions of "OPS235 Lab 4 - Fedora17"

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[[Category:OPS235]][[Category:OPS235 Labs]]
 
[[Category:OPS235]][[Category:OPS235 Labs]]
 +
{{Admon/caution|THIS IS AN OLD VERSION OF THE LAB|'''This is an archived version. Do not use this in your OPS235 course.'''}}
 +
= Storage Setup (prior to starting Lab 4) =
  
 +
At this point, having completed [[OPS235 Lab 3|Lab 3]] you should have <u>roughly</u> the following disk storage setup:<br />
 +
('''Note:''' These results are output from the '''vgs''', '''lvs''', and '''pvs''' commands within each virtual machine. You will be using these commands in the following lab investigations)<br /><br />
  
==Introduction==
+
* '''fedora1'''
  
:* In this lab, you are going to learn how to create and format partitions. You will be creating partitions by using both graphical and command-line using LVM and other Linux utilities.
+
  This VM has a GUI and no free space in the VG.
 +
 +
  VG        #PV #LV #SN Attr  VSize VFree
 +
  vg_fedora1  1  2  0 wz--n- 9.80G    0
 +
 +
  LV      VG        Attr  LSize 
 +
  lv_root vg_fedora1 -wi-ao  8.83G                                   
 +
  lv_swap vg_fedora1 -wi-ao 992.00M                                   
 +
 +
  PV        VG        Fmt  Attr PSize PFree
 +
  /dev/vda2  vg_fedora1 lvm2 a-   9.80G    0
  
:* Also in this lab, you will learn how to manage (add, delete, modify) user accounts on your Fedora systems. You will also learn how to create and maintain groups to allow users to share and protect data.
+
* '''fedora2'''
  
 +
  This VM has a GUI and free space in the VG.
 +
 +
  VG        #PV #LV #SN Attr  VSize VFree
 +
  vg_fedora2  1  3  0 wz--n- 14.80G 4.07G
 +
 +
  LV      VG        Attr  LSize 
 +
  lv_home vg_fedora2 -wi-ao    1.95G                                   
 +
  lv_root vg_fedora2 -wi-ao    7.81G                                   
 +
  lv_swap vg_fedora2 -wi-ao  992.00M                                   
 +
 +
  PV        VG        Fmt  Attr PSize PFree
 +
  /dev/vda2  vg_fedora2 lvm2 a-  14.80G 4.07G
  
==Objectives==
+
* '''fedora3'''
  
#Identify and define major entries in the <code>/etc/passwd</code>, <code>/etc/shadow</code>, and <code>/etc/group</code> files.
+
  This VM has no GUI installed.
#Learn about partitions, and how to add "virtual partitions with LVM.
+
#Learn how to create a "virtual partition" in a Virtual Machine.
+
  VG        #PV #LV #SN Attr  VSize VFree
#Learn how to add and remove and modify user accounts.
+
  vg_fedora3  1  3  0 wz--n- 9.80G 3.83G
#Learn how to create and manage groups.
+
 +
  LV      VG        Attr  LSize 
 +
  lv_home vg_fedora3 -wi-ao  1.00G                                   
 +
  lv_root vg_fedora3 -wi-ao  4.00G                                   
 +
  lv_swap vg_fedora3 -wi-ao 992.00M                                   
 +
 +
  PV        VG        Fmt  Attr PSize PFree
 +
  /dev/vda2  vg_fedora3 lvm2 a-  9.80G 3.83G
  
 +
* '''f17host (i.e. "disk pack")'''
  
==Required Materials (Bring to All Labs)==
+
  Four PVs, minimum VG size 60G
 +
  Single filesystem on vg_main/root, size 50G
 +
  At least 10G available space in VG
 +
 +
  20% of disk space unallocated to any partition (min 15G)
  
* '''Fedora 16 LIVE CD''' - You can burn this onto a CD-R in the Open Lab
+
= Logical Volume Management (Continued) =
* '''Fedora 16 x_64 Installation DVD''' - You can burn this onto a DVD-R in the Open Lab (or burn image onto a DVD+R if you are using the Freedom Toaster).
 
* '''SATA Hard Disk''' (in removable disk tray)
 
* '''USB Memory Stick''' (minimum 64M)
 
* '''Lab Logbook (Lab4 Reference Sheet)''' (to make notes and observations).
 
  
 +
{{Admon/note|Recovering VMs|'''Most of these investigations will take place in you virtual machines.''' If you make a significant mistake, your virtual machine may not boot. Remember that you created backups of your virtual machines in Lab 3, and you can '''restore them if something goes wrong'''.}}
  
==Prerequisites==
+
== Resources ==
  
* Completion and Instructor "Sign-off" of Lab 3: [[OPS235 Lab 3]]
+
'''Please read this page to get an overview of LVM:'''<br /><br />('''Note:''' It is recommended to return to this guide as a reference when performing the next several investigations).<br /><br />
 +
* [[Logical Volume Management]]
  
  
==Linux Command Online Reference==
+
== Investigation 1: How are LVMs are managed using Command-Line Tools  ==
Each Link below displays online manpages for each command (via [http://linuxmanpages.com/ http://linuxmanpages.com]):
+
# You are going to repeat the same LVM management operations (as your did with the ''fedora2'' VM in '''lab3'''), but you will using command-line tools in the '''fedora 3''' VM. Since the fedora3 VM only operates in command-line mode, you will need to refer to the '''"Logical Volume Management"''' link above.
 +
# Write down the exact commands used at each step, and record appropriate command output:
 +
## Determine the current LVM configuration using the <code>pvs</code>, <code>vgs</code>, and <code>lvs</code> command.
 +
## Grow the home filesystem to 2G using the command <code>lvextend</code> and <code>resize2fs</code>.
 +
## Create a new 2G LV containing an ext4 filesystem and mount it at /archive (use <code>lvcreate</code>, <code>mkfs</code>, <code>mount</code>, edit the file <code>/etc/fstab</code>, and then reboot to confirm automatic mount).
 +
## Copy the contents of <code>/etc</code> into <code>/archive</code>.
 +
## Shrink <code>lv_archive</code> to 1G (use <code>umount</code>, <code>resize2fs</code>, <code>lvreduce</code>,  and <code>mount</code>)
  
{|width="100%" cellpadding="5"
+
== Investigation 2: How can a PV be added to an existing VG? ==
|'''LVM Management Utilities:'''
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'''Add an additional 2 GB virtual disk to your ''<u>fedora1</u>'' system, and use it as an additional physical volume:'''
|'''User / Group Management:'''
+
# Start <code>virt-manager</code>.
|
 
|- valign="top"
 
|
 
*[http://linuxmanpages.com/man8/vgs.8.php vgs]
 
*[http://linuxmanpages.com/man8/lvs.8.php lvs]
 
*[http://linuxmanpages.com/man8/pvs.8.php pvs]
 
*[http://linuxmanpages.com/man8/fdisk.8.php fdisk]
 
*[http://linuxmanpages.com/man8/lvextend.8.php lvextend]
 
*[http://linuxmanpages.com/man8/lvcreate.8.php lvcreate]
 
*[http://linuxmanpages.com/man8/pvcreate.8.php pvcreate]
 
*[http://linuxmanpages.com/man8/vgextend.8.php vgextend]
 
*[http://linuxmanpages.com/man8/mount.8.php mount]
 
*[http://linuxmanpages.com/man8/umount.8.php umount]
 
|
 
* [http://linux.die.net/man/5/passwd /etc/passwd File]
 
* [http://www.linuxhowtos.org/Tips%20and%20Tricks/using_skel.htm /etc/skel File]
 
* [http://www.cyberciti.biz/faq/understanding-etcgroup-file/ /etc/group File]
 
*[http://linuxmanpages.com/man8/useradd.8.php useradd]
 
*[http://linuxmanpages.com/man8/userdel.8.php userdel]
 
*[http://linuxmanpages.com/man8/usermod.8.php usermod]
 
*[http://linuxmanpages.com/man8/groupadd.8.php groupadd]
 
*[http://linuxmanpages.com/man8/groupdel.8.php groupdel]
 
*[http://linuxmanpages.com/man1/chmod.1.php chmod]
 
 
 
|}
 
 
 
==Resources on the web==
 
Additional links to tutorials and HOWTOs:
 
 
 
:* [[Logical Volume Management]]
 
:* [http://tldp.org/HOWTO/Partition/fdisk_partitioning.html Partitioning with fdisk]
 
:* [http://www.linux-tutorial.info/modules.php?name=MContent&pageid=282 Mounting / Unmounting File-systems]
 
:* [http://www.itwire.com/content/view/14446/53/ UID and GID explained]
 
 
 
= Creating / Formatting / Mounting Partitions =
 
 
 
{{Admon/note|Do not Shut-Down VMs Until Instructed|You will be running all 3 VMs eventually when performing this tutorial, Leave all VMs running until you are instructed to shut them down at the end of this lab.|}}
 
 
 
== Investigation 1: How to Add a PV to an existing VG (Graphical Method) ==
 
 
 
'''Perform this investigation on the VM named ''<u>fedora1</u>''.'''
 
 
 
In this investigation we will be adding an additional '''2 GB''' virtual disk to our ''<u>'''fedora1'''</u>'' system, and use it as an additional physical volume...
 
 
 
# Start <code>'''virt-manager'''</code>.
 
 
# Shutdown ''fedora1'' if it is running.
 
# Shutdown ''fedora1'' if it is running.
# Open the console window for '''''fedora1'''''.
+
# Open the console window for ''fedora1''.
# Select the menu option '''View'''>'''Details'''.
+
# Select the menu option View>Details.
# Click '''''Add Hardware''''' button at the bottom left-hand corner.
+
# Click ''Add Hardware'' button at the bottom left-hand corner.
# Make certain to remain in the default section called "Storage".
+
# In the ''Adding new virtual hardware'' window that appears, select a Hardware Type of ''"storage"'' and click ''"Forward"''.
# Make the following selections in this "Storage" dialog box:
+
# Make certain option "Managed or other existing storage" is selected. Click on the ''Browse'' button, then click on ''New Volume''.
 
+
# Give the new virtual disk file a name of <code>fedora1b</code>, a format of ''raw'', with a ''Max Capacity'' and ''Allocation'' of 2000 MB. Click ''Finish''.
[[Image:lab4_inv_1.png|thumb|right|400px|Suggested settings in the '''Storage''' dialog box to create a '''virtual Hard Disk'''.]]
+
# Select the new virtual disk file ''fedora1b.img'' and click ''Choose Volume''.
 
+
# Select a device type of ''Virtio Disk''.
::* Under '''Create a disk image on the Computer's Hard Drive''', change the size to '''2 GB'''.
+
# Finish creating the new virtual disk by clicking ''Forward'' and then ''Finish''.
::* Do not click on the '''Select Managed or Other Existing Storage''' radio button. Since no file pathname is provided, then the system will assign a name in the directory <code>/var/lib/libvirt/images/</code>. <!-- CHANGED THIS LINE TO HAVE THE SYSTEM CREATE THE NEW STORAGE FOR THE USER - 2012-02-10 CTyler -->
+
# Boot the system. You should now have both <code>/dev/vda</code> and <code>/dev/vdb</code>.
::* Select Device Type: '''Virtio Disk'''
+
# Record the size of the volume group and the amount of free space (Hint: use a command that you learned in a previous lab).
::* Select Storage Format: '''raw'''
+
# Partition /dev/vdb with a single partition that fills the whole disk.
::* Click '''FINISH''' to proceed.
+
# Check the messages printed when <code>fdisk</code> exits -- you may need to reboot the system in order for the new partition table to take effect.
 
+
# Run this command to format the physical volume: <code>pvcreate /dev/''vdb1''</code>
<ol>
+
# Add the new physical volume to the existing volume group: <code>vgextend ''nameOfVolumeGroup'' /dev/vdb1</code>
  <li value="8">Boot the system. You should now have both <code>/dev/vda</code> and <code>/dev/vdb</code>.</li>
+
# Verify that the volume group is larger and has more free space.
  <li>Record the size of the volume group and the amount of free space (Hint: use a command that you learned in a previous lab).</li>
 
  <li>Use the system-config-lvm tool to add the new virtual disk to the volume group, then extend the size of the root partition using the newly-added space</li>
 
<!-- ### SECTION BELOW CHANGED TO LINE ABOVE 2012-02-10 CTyler BECAUSE THE INSTRUCTIONS BELOW ARE NOT
 
        GRAPHICAL, AND THE TITLE OF THIS SECTION INDICATES THE USE OF THE GRAPHICAL TOOLS! -->
 
<!--
 
  <li>Refer to the following tutorial to use the <code>fdisk</code> command: [http://tldp.org/HOWTO/Partition/fdisk_partitioning.html Partitioning with fdisk]</li>
 
  <li>Use the <code>fdisk</code> command to create a primary partition for <code>/dev/vdb</code> with a single partition (number 1) that fills the whole disk.</li>
 
  <li>Check the messages printed when <code>fdisk</code> exits -- you may need to reboot the system in order for the new partition table to take effect.</li>
 
  <li>Run this command to format the physical volume: <code>pvcreate /dev/''vdb1''</code></li>
 
  <li>Add the new physical volume to the existing volume group: <code>vgextend ''nameOfVolumeGroup'' /dev/vdb1</code></li>
 
  <li>Verify that the volume group is larger and has more free space.</li>
 
-->
 
</ol>
 
 
 
 
 
'''Answer the Investigation 1 observations / questions in your lab log book.'''
 
 
 
== Investigation 2: How to Add a PV to an existing VG (Command Line Method) ==
 
 
 
'''The investigation relate to ''<u>fedora3</u>''.'''
 
 
 
# Check and record the current state of your storage (use <code>df -h, lvs, vgs, pvs</code>).
 
# Make reference to the following command line resource for assistance: [[Logical Volume Management]]
 
#*'''(Hint:''' First view section on '''Adding a Physical Volume'''. Also, write down the commands first and check prior to issuing them in sequence.)
 
# Perform the same operations on ''fedora3'' that you did in the Investigation 1 on ''fedora1'':
 
#* Add a virtual disk to the system.
 
#* Partition the disk (use <code>fdisk</code> - refer to the manpages for details as necessary).
 
#* Make the new partition a physical volume (<code>pvcreate</code>).
 
#* Add the PV to the existing volume group (<code>vgextend</code>).
 
#* Confirm that the VG is now larger (<code>pvs, vgs</code>).
 
#* Extend the root filesystem using the new space (<code>lvextend</code>).
 
#* Confirm that you were successful (<code>lvs, df -h</code>).
 
<!--
 
# You are going to only write in your Lab4 Log-book the Linux commands to perform the same operation that you did graphically in Investigation #1.
 
# You are NOT required to issue these commands on your Fedora3 VM, and it will NOT work since there is no extra room on the VM to create a virtual hard disk -->
 
 
 
 
 
'''Answer the Investigation 2 observations / questions in your lab log book.'''
 
 
 
== Investigation 3: Manually Mounting / Unmounting Partitions ==
 
 
 
'''Perform this investigation on the VM named ''<u>fedora2</u>''.'''
 
 
 
So far, we have simply assumed that when the Fedora OS boots-up, that its file-system is automatically available. In this investigation, you will learn how file-systems (or portions of file-systems) can be mounted or "connected" to existing file-systems. You will also learn how to unmount (or "disconnect") portions of file-systems from existing file-systems.
 
 
 
# Boot-up your '''Fedora2''' VM.
 
# Open a terminal and login as root.
 
# Issue the command called  '''mount''' . This command provides information relating to various partitions (logical volumes) and corresponding "mount points" (directories).
 
# Record the information from issuing the <code>mount</code> command for both '''lv_root''' and '''lv_home'''. What commands would issue to quickly obtain this information?
 
# Issue the command '''umount /archive'''. Did anything happen? Issue the '''mount''' command again. Is there any difference with the command output?
 
# View the online man pages for the [http://linuxmanpages.com/man8/mount.8.php mount] command. Issue the <code>mount</code> command with arguments to "re-connect" the device '''/dev/mapper/vg_fedora2-lv_archive''' to the '''/archive''' directory (refer to the section '''Linux Command Online Reference''' above).
 
 
 
{{Admon/note|File-System Type Option No Longer Required for Mount Command|When viewing examples online, you may notice that the -t option is used with the mount command to indicate the version or type of file-system to mount.<br />'''The -t option is no longer required for the mount command''',|}}
 
 
 
<ol>
 
  <li value="7">Explain how the ''mount'' command would be useful for Linux system administration.</li>
 
  <li>Unmount the '''/archive''' directory.</li>
 
  <li>Issue a command to verify that he '''/archive''' directory has been unmounted.</li>
 
</ol>
 
  
'''Answer the Investigation 3 observations / questions in your lab log book.'''
+
{{Admon/note|Think!|The next part of this investigation requires some research, thought, and creativity.}}
 +
'''Using that additional space, create a separate filesystem for <code>/home</code>:'''
 +
# Create the logical volume <code>lv_home</code> (1G ext4)
 +
# Find a way to move the contents of <code>/home</code> onto it.
 +
# Change your system configuration so that the new filesystem is mounted on <code>/home</code> from now on.
  
 +
{{Admon/tip|SELinux relabelling may be required|Your system may report that the files are not present in the new /home filesystem when they are clearly there. This is due to the Security-Enhanced Linux system (SELinux) preventing access to the files, because the files were tampered with (moved) and are no longer recognized as home directory content. You can fix this problem by restoring the file context labels so that SELinux accepts the files as valid home directory content: <code>restorecon -r /home</code>}}
  
== Investigation 4: How Partitions are Automatically Mounted Upon Boot-up ==
+
== Investigation 3: How can I use LVM to manage storage on my disk pack? ==
 +
'''On your <u>f17host</u> (i.e. "disk pack"), using your choice of the GUI and/or command-line tools:'''
 +
# Create a new logical partition ('''NOT a logical volume!''') - minimum 5G, leaving at least 10G free space in the extended partition.
 +
# Add that partition as a PV into the existing VG (using the commands you used in the previous investigation).
 +
# Grow the root filesystem to fill the available space.
  
'''Perform this investigation on the VM named ''<u>fedora2</u>''.'''
 
 
#Create a directory called '''/storage'''  (i.e. ''storage'' is a subdirectory of the root directory)
 
#Check the man page for <code>/etc/fstab</code> by entering the command <code>man fstab</code>
 
#Edit your <code>/etc/fstab</code> file to mount the partition <code>/dev/mapper/vg_fedora2-lv_archive</code> to <code>'''/storage'''</code>
 
#Issue this command:
 
::<code>mount -a</code>
 
<ol>
 
  <li value="5">What does that command do?</li>
 
  <li>Confirm that the partition mounted.</li>
 
  <li>Issue a command to list the contents of '''/storage'''. Are there any files?
 
  <li>Reboot the fedora2 VM, and verify that '''/storage''' has now been automatically mounted.</li>
 
  <li>In the previous investigation, we mounted the directory as '''/archive''', but in this investigation we automatically mounted it as '''/storage'''. What purpose does could this server for a Linux system administrator?</li>
 
</ol>
 
 
'''Answer the Investigation 4 observations / questions in your lab log book.'''
 
  
  
 
= User/Group Management =
 
= User/Group Management =
  
== Investigation 5: The /etc/passwd file ==
+
== Investigation 4: The /etc/passwd file ==
 
 
'''Perform this investigation on the VM named ''<u>f16host</u>''.'''
 
  
 +
# Look at the /etc/passwd file.
 +
# Make note of the contents of that file.
 
# Read about the file: http://linux.die.net/man/5/passwd  
 
# Read about the file: http://linux.die.net/man/5/passwd  
# Now look at the contents of the '''/etc/passwd''' file.
+
# Make sure you know what information each field contains.
# Make note of the contents of that file, and make certain and record in your lab log-book the information that each field contains.
 
 
# Why do you think there are so many users?
 
# Why do you think there are so many users?
 
# Look at the names of the users. What do you think these user names represent? Are they people?
 
# Look at the names of the users. What do you think these user names represent? Are they people?
Line 197: Line 127:
 
# The user IDs of real users (people) are different from the user IDs of system accounts. What is the pattern?
 
# The user IDs of real users (people) are different from the user IDs of system accounts. What is the pattern?
  
'''Answer the Investigation 5 observations / questions in your lab log book.'''
+
== Investigation 5: Adding users ==
  
 +
{{Admon/note|Use f17host|Perform these steps in the '''f17host''' system. Due to a configuration issue, these steps may not work normally in the fedora1 virtual host (previous versions of this lab used fedora1 for this investigation).}}
  
== Investigation 6: Adding users ==
+
# Read the man page for the useradd command.
 
+
# Create a new user account for each of your pod mates, using their learn account name as a user name. Give each user a password.
'''Perform this investigation on the VM named ''<u>f16host</u>''.'''
+
# Grep the /etc/passwd file for each of the new users.
 
 
# Read the man page for the '''useradd''' command.
 
# Create a new user account for each of your pod-mates, using their learn account name as a user name. Give each user a password.
 
# Use the grep command to obtain information for each of the newly created users within the '''/etc/passwd''' file.
 
 
#* What is the home directory of each user?
 
#* What is the home directory of each user?
 
#* What group is each user in?
 
#* What group is each user in?
Line 214: Line 141:
 
#* Grep the /etc/shadow file for each of the new users.
 
#* Grep the /etc/shadow file for each of the new users.
 
#* Make note of this information.  
 
#* Make note of this information.  
#* What is the purpose of the /etc/shadow file?
 
 
# Create two new dummy users, ops235_1 and ops235_2.
 
# Create two new dummy users, ops235_1 and ops235_2.
 
# Investigate the home directory of one of your new users.
 
# Investigate the home directory of one of your new users.
 
#* What files are there? Be sure to include hidden files.
 
#* What files are there? Be sure to include hidden files.
#* What do you think these files are used for <span  class="plainlinks">?
+
#* What do you think these files are used for?
#* How does the operating system determine which files are created in a new home account? <br />The answer can be found here: http://www.linuxhowtos.org/Tips%20and%20Tricks/using_skel.htm
+
#* How does the operating system determine which files are created in a new home account? The answer can be found here: http://www.linuxhowtos.org/Tips%20and%20Tricks/using_skel.htm
 
#* Look at the files (including hidden files) in the template directory referred to in the article. Compare them to what is in a home directory for a new user. What do you notice?
 
#* Look at the files (including hidden files) in the template directory referred to in the article. Compare them to what is in a home directory for a new user. What do you notice?
 
#* Create a new file in this directory with the following command: <code>touch foo</code>
 
#* Create a new file in this directory with the following command: <code>touch foo</code>
 
#* Create a new user named foobar, with the option to automatically create a home directory.
 
#* Create a new user named foobar, with the option to automatically create a home directory.
 
#* Look at the contents of foobar's home directory. What do you notice?
 
#* Look at the contents of foobar's home directory. What do you notice?
 +
# Be sure to record your observations in your lab notes.
  
<ol>
+
{{Admon/note|Use fedora3|Perform these steps in the '''fedora3''' virtual machine.}}
  <li value="7">Boot-up your '''fedora3''' VM.</li>
+
# Add your matrix account user to '''fedora3'''.
  <li>Create a new user using your '''Matrix''' account user-name.</li>
 
  <li>Issue a command to verify that you have created this user account.</li>
 
</ol>
 
  
'''Answer the Investigation 6 observations / questions in your lab log book.'''
+
== Investigation 6: Managing Groups ==
 
 
 
 
== Investigation 7: Managing Groups ==
 
  
 
{{Admon/note|Use fedora1|Perform these steps in the '''fedora1''' virtual machine.}}
 
{{Admon/note|Use fedora1|Perform these steps in the '''fedora1''' virtual machine.}}
  
<ol>
+
# Read the man page for the groupadd and groupdel commands.
<li>Read the man page for the '''groupadd''' and '''groupdel''' commands.</li>
+
# Note which option allows you to set the Group ID number (GID) when you create a new group.
<li>Note which option allows you to set the Group ID number (GID) when you create a new group.</li>
+
# Examine the file /etc/group
<li>Examine the file <code>/etc/group</code>
+
#* Which values of GID are reserved for system accounts?
<ol type="a">
+
#* Which values of GID are reserved for non-system user accounts?
<li>Which values of GID are reserved for system accounts?</li>
+
#8 What is the lowest available GID number for non-system users?
<li>Which values of GID are reserved for non-system user accounts?</li>
+
#* What is the default group name of a new user?
<li>What is the lowest available GID number for non-system users?</li>
+
#* Add a new group named ops235 with a GID of 600.
<li>What is the default group name of a new user?</li>
+
#* You are angry at some irresponsible users on your system.
<li>Add a new group named <code>ops235</code> with a GID of <code>600</code>.</li>
+
#** Add a new group named idiots.
<li>You are angry at some irresponsible users on your system.
+
#** Look at /etc/group and note the GID of idiots.
<ul>
+
#** What GID is given to a new group if if you do not specify it?
<li>Add a new group named <code>idiots</code>.</li>
+
#**  Your anger has subsided. Delete the idiots group.
<li>Look at <code>/etc/group</code> and note the GID of idiots.</li>
+
#** Look at /etc/group again and note the change.
<li>What GID is given to a new group if you do not specify it?</li>
 
<li>Your anger has subsided. Delete the <code>idiots</code> group.</li>
 
<li>Look at <code>/etc/group</code> again and note the change.</li>
 
</ul>
 
</li>
 
</li>
 
</ol>
 
</li>
 
</ol>
 
  
 
Be sure to record your observations in your lab notes.
 
Be sure to record your observations in your lab notes.
  
'''Answer the Investigation 7 observations / questions in your lab log book.'''
+
== Investigation 7: Deleting users ==
 
 
 
 
== Investigation 8: Deleting users ==
 
  
 
{{Admon/note|Use fedora1|Perform these steps in the '''fedora1''' virtual machine.}}
 
{{Admon/note|Use fedora1|Perform these steps in the '''fedora1''' virtual machine.}}
  
# Read the man page for the '''userdel''' command. Note which option automatically removes the users home directory when that user is deleted.
+
# Read the man page for the userdel command. Note which option automatically removes the users home directory when that user is deleted.
  
 
# Delete the user ops235_1 using the command <code>userdel ops235_1</code>
 
# Delete the user ops235_1 using the command <code>userdel ops235_1</code>
# Delete the user <code>ops235_2</code> using the same command with the option which removes the home directory of the user.
+
# Delete the user ops235_2 using the same command with the option which removes the home directory of the user.
# Check the contents of the <code>/home</code> directory. What do you notice?
+
# Check the contents of the /home directory. What do you notice?
# Check the contents of the <code>/etc/group</code> directory. What do you notice?
+
# Check the contents of the /etc/group file. What do you notice?
  
'''Answer the Investigation 8 observations / questions in your lab log book.'''
+
Be sure to record your observations in your lab notes.
  
 +
== Investigation 8: Modifying users ==
  
== Investigation 9: Modifying users ==
+
{{Admon/note|Use fedora1|Perform these steps in the '''fedora1''' virtual machine.}}
 
 
  
'''Perform this investigation on the VM named ''<u>fedora1</u>''.'''
+
# Read the man page for the usermod command. Note which options change the user's full name, primary group, supplementary groups, and shell.
  
# Read the man page for the '''usermod''' command. Note which options change the user's full name, primary group, supplementary groups, and shell.
+
# Add each of your new users to the group ops235 (in other words, add ops235 to each user as a supplementary group).
# Create a new user account for each of your pod-mates again, but this time for your <code>fedora1</code> VM, using their learn account name as a user name. Give each user a password.
 
# Add each of your new pod mate accounts to the group <code>ops235</code> (in other words, add ops235 to each user as a supplementary group).
 
 
# Examine <code>/etc/group</code>. What has changed?
 
# Examine <code>/etc/group</code>. What has changed?
# Experiment with your pod-mate accounts to share and deny access to same group members by creating directories and files, and use the <code>chmod</code> command. How is the <code>/etc/group</code> related to file sharing permissions?
+
# Use the usermod command to associate each of your pod mates' full name to their user name, as shown in your text. With each change, examine their entries in the <code>/etc/passwd</code> file. What has changed?
# Use the <code>usermod</code> command to associate each of your pod mates' full name to their user name, as shown in your text. With each change, examine their entries in the <code>/etc/passwd</code> file. What has changed?
 
# Just for interest, how would you use a graphical utility to modify user account information?
 
 
# Be sure to record your observations in your lab notes.
 
# Be sure to record your observations in your lab notes.
  
{{Admon/important|Shutdown VMs|It is time to safely shut-down all of your Virtual Machines. Please proceed to '''Completing the Lab'''}}
 
 
 
'''Answer the Investigation 9 observations / questions in your lab log book.'''
 
  
 
<!-- == Investigation 13: Security Tip: Removing Unnecessary Users and Groups ==
 
<!-- == Investigation 13: Security Tip: Removing Unnecessary Users and Groups ==
Line 325: Line 226:
 
#* nscd (if not using nscd)
 
#* nscd (if not using nscd)
 
#* uucp -->
 
#* uucp -->
 
  
 
= Completing the lab =
 
= Completing the lab =
Line 332: Line 232:
  
 
Arrange proof of the following on the screen:
 
Arrange proof of the following on the screen:
# Increased volume group size for '''fedora1''' VM.
+
# Two PVs on '''fedora1'''.
# Correct Linux command sequence to Add a PV to an exiting VG
+
# Separate <code>/home</code> filesystem (on an LV) in '''fedora1'''.
# <code>/etc/fstab</code> entry in '''fedora2''' VM to automatically mount <code>/storage</code>
+
<!-- # Unnecessary accounts and groups have been removed on '''fedora1'''. -->
# Proof of ops235 group entry in <code>/etc/group</code> in '''fedora1''' VM
+
# Account created on '''fedora3''' matching your Matrix account.
# Proof of pod-mate user account information in <code>/etc/passwd</code> in '''fedora1''' VM.
+
# List contents of '''/etc/group''' file (ops235 group).
# Proof of VM backups.
+
# List contents of '''/etc/passwd''' file (created accounts).
 
+
# Fresh backup of the virtual machines.
  
 
= Preparing for the Quizzes =
 
= Preparing for the Quizzes =
  
# What is the reason to extend a Volume Group?
+
# What is a VG? PV? LV?  
# What is the purpose of the file called <code>/etc/fstab</code>?
+
# What is the total size of the "main" VG on your system?
# How do you ensure that a file-system is mounted every time that a system is started?
+
# How do you create a LV?
# What are the purposes of the following files: <code>/etc/passwd</code>, <code>/etc/shadow</code>, <code>/etc/group</code>?
+
# How do you delete an LV?
# Explain the purpose of the <code>/etc/skel</code> directory.
+
# How would you add the disk partition <code>/dev/sdb7</code> to your volume group "main"?
# What do the terms <code>UID</code> and <code>GID </code>represent. What is their purpose?
+
# How would you increase the size of the root filesystem by 50 MB?
# List the steps to create a user account on a system.
+
# What is the purpose of <code>/etc/fstab</code>?
# List the steps to change user account information on a system.
+
# What is the purpose of <code>/etc/shadow</code>?
# List the steps in order for users to share file and directory accounts as "same group members".
 
# List the steps to remove a user account. What is required to remove a user account's home directory as well?
 

Latest revision as of 11:31, 24 September 2018

Stop (medium size).png
THIS IS AN OLD VERSION OF THE LAB
This is an archived version. Do not use this in your OPS235 course.

Storage Setup (prior to starting Lab 4)

At this point, having completed Lab 3 you should have roughly the following disk storage setup:
(Note: These results are output from the vgs, lvs, and pvs commands within each virtual machine. You will be using these commands in the following lab investigations)

  • fedora1
 This VM has a GUI and no free space in the VG.

 VG         #PV #LV #SN Attr   VSize VFree
 vg_fedora1   1   2   0 wz--n- 9.80G    0

 LV      VG         Attr   LSize  
 lv_root vg_fedora1 -wi-ao   8.83G                                     
 lv_swap vg_fedora1 -wi-ao 992.00M                                     

 PV         VG         Fmt  Attr PSize PFree
 /dev/vda2  vg_fedora1 lvm2 a-   9.80G    0
  • fedora2
 This VM has a GUI and free space in the VG.

 VG         #PV #LV #SN Attr   VSize VFree
 vg_fedora2   1   3   0 wz--n- 14.80G 4.07G

 LV      VG         Attr   LSize   
 lv_home vg_fedora2 -wi-ao    1.95G                                     
 lv_root vg_fedora2 -wi-ao    7.81G                                     
 lv_swap vg_fedora2 -wi-ao  992.00M                                     

 PV         VG         Fmt  Attr PSize PFree
 /dev/vda2  vg_fedora2 lvm2 a-   14.80G 4.07G
  • fedora3
 This VM has no GUI installed.

 VG         #PV #LV #SN Attr   VSize VFree
 vg_fedora3   1   3   0 wz--n- 9.80G 3.83G

 LV      VG         Attr   LSize  
 lv_home vg_fedora3 -wi-ao   1.00G                                     
 lv_root vg_fedora3 -wi-ao   4.00G                                     
 lv_swap vg_fedora3 -wi-ao 992.00M                                     

 PV         VG         Fmt  Attr PSize PFree
 /dev/vda2  vg_fedora3 lvm2 a-   9.80G 3.83G
  • f17host (i.e. "disk pack")
 Four PVs, minimum VG size 60G
 Single filesystem on vg_main/root, size 50G
 At least 10G available space in VG

 20% of disk space unallocated to any partition (min 15G)

Logical Volume Management (Continued)

Recovering VMs
Most of these investigations will take place in you virtual machines. If you make a significant mistake, your virtual machine may not boot. Remember that you created backups of your virtual machines in Lab 3, and you can restore them if something goes wrong.

Resources

Please read this page to get an overview of LVM:

(Note: It is recommended to return to this guide as a reference when performing the next several investigations).


Investigation 1: How are LVMs are managed using Command-Line Tools

  1. You are going to repeat the same LVM management operations (as your did with the fedora2 VM in lab3), but you will using command-line tools in the fedora 3 VM. Since the fedora3 VM only operates in command-line mode, you will need to refer to the "Logical Volume Management" link above.
  2. Write down the exact commands used at each step, and record appropriate command output:
    1. Determine the current LVM configuration using the pvs, vgs, and lvs command.
    2. Grow the home filesystem to 2G using the command lvextend and resize2fs.
    3. Create a new 2G LV containing an ext4 filesystem and mount it at /archive (use lvcreate, mkfs, mount, edit the file /etc/fstab, and then reboot to confirm automatic mount).
    4. Copy the contents of /etc into /archive.
    5. Shrink lv_archive to 1G (use umount, resize2fs, lvreduce, and mount)

Investigation 2: How can a PV be added to an existing VG?

Add an additional 2 GB virtual disk to your fedora1 system, and use it as an additional physical volume:

  1. Start virt-manager.
  2. Shutdown fedora1 if it is running.
  3. Open the console window for fedora1.
  4. Select the menu option View>Details.
  5. Click Add Hardware button at the bottom left-hand corner.
  6. In the Adding new virtual hardware window that appears, select a Hardware Type of "storage" and click "Forward".
  7. Make certain option "Managed or other existing storage" is selected. Click on the Browse button, then click on New Volume.
  8. Give the new virtual disk file a name of fedora1b, a format of raw, with a Max Capacity and Allocation of 2000 MB. Click Finish.
  9. Select the new virtual disk file fedora1b.img and click Choose Volume.
  10. Select a device type of Virtio Disk.
  11. Finish creating the new virtual disk by clicking Forward and then Finish.
  12. Boot the system. You should now have both /dev/vda and /dev/vdb.
  13. Record the size of the volume group and the amount of free space (Hint: use a command that you learned in a previous lab).
  14. Partition /dev/vdb with a single partition that fills the whole disk.
  15. Check the messages printed when fdisk exits -- you may need to reboot the system in order for the new partition table to take effect.
  16. Run this command to format the physical volume: pvcreate /dev/vdb1
  17. Add the new physical volume to the existing volume group: vgextend nameOfVolumeGroup /dev/vdb1
  18. Verify that the volume group is larger and has more free space.
Think!
The next part of this investigation requires some research, thought, and creativity.

Using that additional space, create a separate filesystem for /home:

  1. Create the logical volume lv_home (1G ext4)
  2. Find a way to move the contents of /home onto it.
  3. Change your system configuration so that the new filesystem is mounted on /home from now on.
SELinux relabelling may be required
Your system may report that the files are not present in the new /home filesystem when they are clearly there. This is due to the Security-Enhanced Linux system (SELinux) preventing access to the files, because the files were tampered with (moved) and are no longer recognized as home directory content. You can fix this problem by restoring the file context labels so that SELinux accepts the files as valid home directory content: restorecon -r /home

Investigation 3: How can I use LVM to manage storage on my disk pack?

On your f17host (i.e. "disk pack"), using your choice of the GUI and/or command-line tools:

  1. Create a new logical partition (NOT a logical volume!) - minimum 5G, leaving at least 10G free space in the extended partition.
  2. Add that partition as a PV into the existing VG (using the commands you used in the previous investigation).
  3. Grow the root filesystem to fill the available space.


User/Group Management

Investigation 4: The /etc/passwd file

  1. Look at the /etc/passwd file.
  2. Make note of the contents of that file.
  3. Read about the file: http://linux.die.net/man/5/passwd
  4. Make sure you know what information each field contains.
  5. Why do you think there are so many users?
  6. Look at the names of the users. What do you think these user names represent? Are they people?
  7. What is the numeric user ID (UID) of the root user?
  8. The user IDs of real users (people) are different from the user IDs of system accounts. What is the pattern?

Investigation 5: Adding users

Use f17host
Perform these steps in the f17host system. Due to a configuration issue, these steps may not work normally in the fedora1 virtual host (previous versions of this lab used fedora1 for this investigation).
  1. Read the man page for the useradd command.
  2. Create a new user account for each of your pod mates, using their learn account name as a user name. Give each user a password.
  3. Grep the /etc/passwd file for each of the new users.
    • What is the home directory of each user?
    • What group is each user in?
    • What else do you know about each user?
    • Where are the passwords stored?
  4. Look at the man page for /etc/shadow using the command man 5 shadow
    • Grep the /etc/shadow file for each of the new users.
    • Make note of this information.
  5. Create two new dummy users, ops235_1 and ops235_2.
  6. Investigate the home directory of one of your new users.
    • What files are there? Be sure to include hidden files.
    • What do you think these files are used for?
    • How does the operating system determine which files are created in a new home account? The answer can be found here: http://www.linuxhowtos.org/Tips%20and%20Tricks/using_skel.htm
    • Look at the files (including hidden files) in the template directory referred to in the article. Compare them to what is in a home directory for a new user. What do you notice?
    • Create a new file in this directory with the following command: touch foo
    • Create a new user named foobar, with the option to automatically create a home directory.
    • Look at the contents of foobar's home directory. What do you notice?
  7. Be sure to record your observations in your lab notes.
Use fedora3
Perform these steps in the fedora3 virtual machine.
  1. Add your matrix account user to fedora3.

Investigation 6: Managing Groups

Use fedora1
Perform these steps in the fedora1 virtual machine.
  1. Read the man page for the groupadd and groupdel commands.
  2. Note which option allows you to set the Group ID number (GID) when you create a new group.
  3. Examine the file /etc/group
    • Which values of GID are reserved for system accounts?
    • Which values of GID are reserved for non-system user accounts?
  4. 8 What is the lowest available GID number for non-system users?
    • What is the default group name of a new user?
    • Add a new group named ops235 with a GID of 600.
    • You are angry at some irresponsible users on your system.
      • Add a new group named idiots.
      • Look at /etc/group and note the GID of idiots.
      • What GID is given to a new group if if you do not specify it?
      • Your anger has subsided. Delete the idiots group.
      • Look at /etc/group again and note the change.

Be sure to record your observations in your lab notes.

Investigation 7: Deleting users

Use fedora1
Perform these steps in the fedora1 virtual machine.
  1. Read the man page for the userdel command. Note which option automatically removes the users home directory when that user is deleted.
  1. Delete the user ops235_1 using the command userdel ops235_1
  2. Delete the user ops235_2 using the same command with the option which removes the home directory of the user.
  3. Check the contents of the /home directory. What do you notice?
  4. Check the contents of the /etc/group file. What do you notice?

Be sure to record your observations in your lab notes.

Investigation 8: Modifying users

Use fedora1
Perform these steps in the fedora1 virtual machine.
  1. Read the man page for the usermod command. Note which options change the user's full name, primary group, supplementary groups, and shell.
  1. Add each of your new users to the group ops235 (in other words, add ops235 to each user as a supplementary group).
  2. Examine /etc/group. What has changed?
  3. Use the usermod command to associate each of your pod mates' full name to their user name, as shown in your text. With each change, examine their entries in the /etc/passwd file. What has changed?
  4. Be sure to record your observations in your lab notes.


Completing the lab

Time for a new backup!
If you have successfully completed this lab, make a new backup of your virtual machines. Remember to also make a backup of the new second virtual disk drive on fedora1 -- you now have two virtual disks on fedora1, and therefore two image files, and therefore will need two backup files.

Arrange proof of the following on the screen:

  1. Two PVs on fedora1.
  2. Separate /home filesystem (on an LV) in fedora1.
  3. Account created on fedora3 matching your Matrix account.
  4. List contents of /etc/group file (ops235 group).
  5. List contents of /etc/passwd file (created accounts).
  6. Fresh backup of the virtual machines.

Preparing for the Quizzes

  1. What is a VG? PV? LV?
  2. What is the total size of the "main" VG on your system?
  3. How do you create a LV?
  4. How do you delete an LV?
  5. How would you add the disk partition /dev/sdb7 to your volume group "main"?
  6. How would you increase the size of the root filesystem by 50 MB?
  7. What is the purpose of /etc/fstab?
  8. What is the purpose of /etc/shadow?